Pyrazolidinone salts as developing agents

ABSTRACT

Salts of 1-phenyl-3-pyrazolidinones which are useful photographic silver halide developing agents.

The present invention relates to novel developing agents.

It is well know that certain pyrazolidinone compounds are useful ascomponents of photographic developing compositions, as described, forexample, in chapter 11 of the book "The Theory of the PhotographicProcess", 4th edition, edited by T. H. James and published by Macmillan.An example of such a compound is 1-phenylpyrazolidinone of the formula##STR1## However, although widely used, developing agents of thepyrazolidinone class do suffer from certain disadvantages in their use.One disadvantage is that they only dissolve slowly in water, and thuselevated temperatures or prolonged stirring are necessary in order tomake up solutions containing compounds such as the compound of theformula (1). A second disadvantage of such compounds is that they aresusceptible to oxidation. It is known that said compounds may berendered resistant to oxydation by use of a suitable protecting group toreplace the labile N--H group. A particularly effective means ofachieving this is described in GB 1 006 320, in which the N--H group isreplaced by a substituted amino methyl group. This is an advantageousprotecting group because it is removed by sulphite to regenerate theoriginal pyrazolidinone compound. However, the protected pyrazolidinonecompounds described in GB 1 006 320 still only dissolve slowly in water,and, particularly in the presence of other compounds, tend to produceoily or gummy deposits which do not dissolve in water even after a longperiod. Thus the protected developing agents of GB 1 006 320 can not beused in single bag developer compositions because of the formation ofthe oil or gummy deposits when water is added to dissolve the powderedmixture.

We have now prepared new salts of protected pyrazolidinone compoundswhich overcome these disadvantages. These new salts are readily solublein water even in the presence of other components, and the resultingsolutions are active as photographic developing compositions.

According to the present invention there are provided novel developingagents, which are 1-pyrazolidinone salts of the formula ##STR2## inwhich X.sup.⊖ is an anion, which may be organic or inorganic, Lrepresents the atoms necessary to complete a saturated ring or ringsystem, which may be substituted,

R₁ is phenyl or substituted phenyl,

R₂ and R₃ are each hydrogen, lower alkyl or substituted lower alkyl,

R₄ and R₅ are each hydrogen, lower alkyl, substituted lower alkyl,phenyl or substituted phenyl.

By lower alkyl is meant an alkyl group containing 1 to 4 carbon atoms,for example methyl, ethyl, propyl, isopropyl, or butyl groups.

Suitable substituents for the alkyl groups R₂, R₃, R₄ and R₅ includehydroxyl, alkoxy, aryloxy, preferably phenoxy or amino groups.

Suitable substituents for the phenyl groups R₁, R₄ or R₅ include alkyl,alkoxy, chloro, hydroxyl or amino substituents. Preferably, the group R₁is unsubstituted phenyl or p-tolyl.

Suitable anions X.sup.⊖ include halide ions such as chloride or bromide,and the anions of organic sulphonic acids, for example p-toluenesulphonate, benzene sulphonate, methane sulphonate, 3-hydroxypropanesulphonate and 5-sulphosalicylate.

Preferably, the groups R₁ are p-tolyl or p-anisyl and more preferablyphenyl.

Suitable groups R₂ and R₃ are hydrogen, methyl, hydroxymethyl orhydroxyethyl.

Preferably, the groups R₄ and R₅ are both hydrogen.

Preferably, in order to keep the molecular weight down, the heterocyclicring including the group L is a simple saturated ring such aspyrrolidine, piperidine or morpholine, or alternatively is a piperazinering which has been substituted at the 4-position with anotherpyrazolidinone ring to give a compound of the formula ##STR3## in whichR₁, R₂, R₃, R₄, R₅ and X.sup.⊖ are as defined above.

Alternatively, both of the nitrogen atoms of a substituted piperazinecompound may be used for salt formation, to give a compound of theformula ##STR4## in which R₁, R₂, R₃, R₄, R₅ and X.sup.⊖ have themeanings assigned above.

Compounds of the formula (2) may be prepared by treatment of a compoundof the formula ##STR5## in which R₁, R₂, R₃, R₄, R₅, X and L have themeanings assigned above, with an acid HX in a suitable solvent andinducing crystallisation.

Suitable solvents include ethers such as tetrahydrofuran or dioxan,esters such as ethyl acetate, and ketones such as acetone. Preferablythe compound of the formula (5) and the acid HX are used in a 1:1stoichiometry; however, if it is desired to produce a bis-salt offormula (4) then a 1:2 ratio should be used. Solvents are chosen inwhich both the acid HX and the pyrazolidinone of formula (5) are readilysoluble such that a one phase reaction may be used.

Compounds of formula (5) are described in GB 1 006 320, and may beprepared by the methods described therein, that is by reaction between apyrazolidinone, formaldehyde, and a secondary amine.

Another embodiment of the present invention is a photographic processingcomposition containing a salt of the formula (2) together with othercomponents commonly found in processing compositions, such as developingagents, for example, hydroquinone or substituted hydroquinone, bases orbuffer systems such as for example sodium carbonate, or sodiumtetraborate/boric acid, respectively, antioxidants or preservatives, forexample sodium sulphite, restrainers for example sodium bromide, andantifoggants for example benzotriazole.

The following examples will serve to illustrate the invention.

EXAMPLE 1

Preparation of the compound of the formula ##STR6##

The precursor or 2-morpholino-methyl-1-phenyl pyrazolidinone wasprepared as in Example 1 of GB 1 006 320. 3.2 grams of this compound wasdissolved in acetone (15 ml) and p-toluene sulphonic acid monohydrate(2.5 g) was added. The solution was heated under reflux for 5 minutes,cooled in ice and the white crystalline solid product filtered off andwashed with a little ether, yield 3.3 g (63%), melting point 139°-141°C.

EXAMPLE 2

Preparation of the compound of the formula ##STR7##

This compound was prepared in exactly the same fashion as the compoundof the formula A, but using piperidine instead of morpholine. Theproduct has a melting point of 126°-128° C.

EXAMPLE 3

Preparation of the compound of the formula (D) from the intermediate ofthe formula (C) which has the formula ##STR8##

40% (W/W) Formalin (4.4 ml) was added to a solution of piperazine (2.15g) in methanol (25 ml). After 10 minutes,4-methyl-4-hydroxymethyl-1-phenyl-3-pyrazolidinone (10.3 g) was addedand the yellow solution was heated under reflux for 12 hours. Thesolvents were evaporated and the solid product was recrystallised fromethyl acetate (80 ml), yield 8.45 g (65%), melting point 181°-185° C.The compound of the formula (D), which has the formula below wasprepared from the intermediate of the formula (C). ##STR9##

The intermediate of the formula (C) (1.0 g) in tetrahydrofuran (40 ml)and dichloromethane (50 ml) was mixed with 4.5% w/v hydrobromic acid inacetic acid (0.4 ml) at room temperature. After stirring for 1 hour, thesolid compound of the formula (D) was filtered off and washed with alittle ether, yield 0.65 g (57%), melting point 177°-181° C.

EXAMPLE 4

Other salts of the intermediate of the formula (C) were prepared by thesame techniques:

    ______________________________________                                        Compound of the formula                                                                      Anion          melting point                                   ______________________________________                                        (E)            p-toluene sulphonate                                                                          95-101° C.                              (F)            5-sulphosalicylate                                                                           113-117° C.                              (G)            benzene sulphonate                                                                           102-108° C.                              ______________________________________                                    

EXAMPLE 5

Preparation of the intermediate of the formula ##STR10##

40% (W/W) Formalin (4.25 ml) was added to a solution of piperazine (2.15g) in ethanol (50 ml) at 5° C. After 10 minutes,1-phenyl-3-pyrazolidinone (8.1 g) was added and the yellow solutionheated under reflux for 6 hours. The solvent was evaporated and thecolourless crystalline product recrystallised from methanol, yield 6.93g (64%), melting point 194°-195° C.

The compound of the formula ##STR11## was prepared from the intermediateof the formula (H).

Intermediate of the formula (H) (0.75 g) was dissolved intetrahydrofuran (50 ml) and a solution of p-toluene sulphonic acidmonohydrate (0.69 g) (i.e. 2 equivalents) in tetrahydrofuran was addedand the white precipitate filtered off and washed with ether, yield 1.12g, melting point 117°-120° C.

EXAMPLE 6

Further salts (1:1) were prepared from the intermediate of the formula(H) of the general formula

    ______________________________________                                         ##STR12##                                                                    Compound of the formula                                                                      Anion          melting point                                   ______________________________________                                        (J)            p-toluene sulphonate                                                                         125-129° C.                              (K)            benzene sulphonate                                                                           142-148° C.                              (L)            methane sulphonate                                                                           159-162° C.                              (M)            3-hydroxypropane                                                                             113-117° C.                                             sulphonate                                                     (N)            5-sulphosalicylate                                                                           85-90° C.                                (O)            chloride       164-167° C.                              (P)            bromide        168-172° C.                              ______________________________________                                    

In all the compounds of the formulae (A) to (P) n.m.r. spectroscopy wasused to show the structure and the nature and stoichiometry of thesalts.

EXAMPLE 7

Single bag developer powders were prepared containing the followingingredients:

    ______________________________________                                        Hydroquinone       1.5 g                                                      Boric Acid         0.8 g                                                      Sodium Tetraborate 2.0 g                                                      Potassium Bromide  0.3 g                                                      Sodium Sulphite    25.0 g-30 g                                                                   (depending on salt used)                                   Pyrazolidinone Salt                                                                              0.05 g-0.5 g                                               or                 (depending on salt used)                                   Pyrazolidinone Compound                                                                          0.1 g                                                      ______________________________________                                    

The well known and widely used pyrazolidinone silver halide developingagents 1-phenyl-3-pyrazolidinone (Test I) and4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidinone (Test II) were alsoused as comparison compounds.

The pyrazolidinone type compounds used were the previously knowncompound of formula ##STR13## of Example 1 of GB 1 006 320 and thecompounds of the formulae (A), (B) and (J) of the present invention.

The tests were carried out by mixing the above quantities of ingredientsin a paper/foil laminate bag and heat-sealing.

Solubility tests were carried out by measuring the time taken for thecontents of the bags to dissolve in 280 ml of water at 20° C. withgentle stirring. The results are given in the table below:

                  TABLE                                                           ______________________________________                                        Sample containing                                                             compound of the formula                                                                     Time to Dissolve                                                ______________________________________                                        (6), comparison                                                                             Does not at all dissolve - forms an oil                         (A), present invention                                                                      20 Seconds                                                      (B), present invention                                                                      2 Minutes                                                       (J), present invention                                                                      5 Minutes                                                       Test I, comparison                                                                          Greater than 20 minutes                                         Test II, comparison                                                                         Greater than 20 minutes                                         ______________________________________                                    

Thus the previously known compounds are not readily soluble at 20° C.,whereas the compounds of the present invention dissolve rapidly at 20°C.

The photographic activity of the liquid developer compositions whichcomprised salts of formulae (A), (B) and (J) were compared with afreshly made up solution which contained 1-phenyl-3-pyrazolidinone whichwas dissolved up at 50° C. with constant stirring.

All these developing solutions made from powder compositions were veryactive silver halide developing solutions and as good as that made fromthe compound of the formula (1). Thus all the compounds of the presentinvention are of great use as silver halide developing agents and whenformulated as single powder developer compositions give rapidlydissolving formulations.

We claim:
 1. A 1-phenyl-3-pyrazolidinone salt of the formula ##STR14##in which X.sup.⊖ is an organic anion,L represents the atoms necessary tocomplete an unsubstituted pyrrolidine, piperidine or morpholine ring, R₁is phenyl which is unsubstituted or substituted by alkyl, alkoxy,chloro, hydroxyl or amino, R₂ and R₃ are each hydrogen or lower alkylwhich is unsubstituted or substituted by hydroxyl, alkoxy, aryloxy oramino, and R₄ and R₅ are each hydrogen, lower alkyl which isunsubstituted or substituted by hydroxyl, alkoxy, aryloxy or amino, orphenyl which is unsubstituted or substituted by alkyl, alkoxy, chloro,hydroxyl or amino.
 2. A 1-phenyl-3-pyrazolidinone salt of the formula##STR15##
 3. A 1-phenyl-3-pyrazolidinone salt according to claim 1,wherein R₂ and R₃ are each hydrogen, methyl, hydroxymethyl orhydroxyethyl.
 4. A 1-phenyl-3-pyrazolidinone salt according to claim 1,wherein R₄ and R₅ are each hydrogen.
 5. A 1-phenyl-3-pyrazolidinone saltaccording to claim 1, wherein R₁ is phenyl, p-tolyl or p-anisyl.